exports.createXHR = function(){

        if(typeof XMLHttpRequest != "undefined"){
            return new XMLHttpRequest();
        }else if(typeof ActiveXObject != "undefined"){
            if(typeof arguments.callee.activeXString != "string"){
                var version = ["MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.3.0","MSXMl2.XMLHttp"];
                var i;
                var len;
    
                for(i =0,len =version.length;i<len;i++){
                    try{
                        new ActiveXObject(version[i]);
                        arguments.callee.activeXString = version[i];
                        break;
                    }catch(ex){
                        
                    }
                }
            }
            return new ActiveXObject(arguments.callee.activeXString);
    
        }else{
            throw new Error("没有xhr对象")
        }
}



